TWI864790B - Substrate processing method and substrate processing apparatus - Google Patents

Abstract

The present invention aims to provide a substrate processing method and a substrate processing device that can reliably suppress pattern collapse. The present invention supplies a constant amount of IPA to the substrate W after the cleaning process from the processing liquid nozzle 30. By pre-drying, the liquid level of IPA gradually decreases. When the liquid level of IPA is consistent with the upper end of the support of the pattern formed on the substrate W, the surface of the substrate W is irradiated with flash light from the flash lamp FL to evaporate the residual IPA instantly. By irradiating the flash light with extremely short irradiation time and high intensity, the drying time required from the start of capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate W is shorter than the collapse time required from the start of capillary force acting on the pattern to the collapse of the pattern. Even for patterns that are relatively large in both vertical and horizontal dimensions, the pattern collapse can be reliably suppressed.

Description

Substrate processing method and substrate processing device

The present invention relates to a substrate processing method and a substrate processing device for drying a substrate formed with a fine pattern. The substrate to be processed includes, for example, a semiconductor substrate, a substrate for a liquid crystal display device, a substrate for a flat panel display (FPD), a substrate for an optical disk, a substrate for a magnetic disk, or a substrate for a solar cell.

Conventionally, in the manufacturing process of semiconductor devices, various processing processes such as cleaning, film formation, and heat treatment are performed on semiconductor substrates (hereinafter referred to as "substrates"). One of such processing processes is a drying process for drying the wet substrate that has been wet-cleaned or the like.

In recent years, with the progress of miniaturization, nanostructure patterns with relatively large length and width are sometimes formed on the substrate. In the drying process, there is a problem of collapse of such nanostructures with relatively large length and width. It has been determined that the main reason for the collapse of nanostructures in the drying process is the capillary force (capillary force) of the liquid attached to the substrate acting on the nanostructure during the drying process. For this problem, the most commonly adopted countermeasure is to use a liquid with low surface tension as the processing liquid during drying, typically using IPA (isopropanol). Since capillary force depends on the surface tension of the liquid, by using a liquid with low surface tension such as IPA as the processing liquid during drying, the capillary force acting on the nanostructure pattern can be reduced and the pattern collapse can be suppressed.

On the other hand, Patent Document 1 discloses a technique for preventing pattern collapse by irradiating a substrate after cleaning with a flash lamp to cause instant evaporation of water. [Prior Technical Document]

[Patent Document 1] Japanese Patent Publication No. 2007-19158

[The problem the invention is trying to solve]

However, even when using a liquid with low surface tension such as IPA, the surface tension will not reach 0, so there is a limit to reducing the capillary force acting on the pattern. In addition, even when drying by flash irradiation, it is difficult to fully prevent the pattern from collapsing, especially in the next generation nanostructure pattern with an aspect ratio of more than 15.

The present invention is made in view of the above-mentioned problems, and its purpose is to provide a substrate processing method and substrate processing device that can reliably suppress pattern collapse. [Technical means for solving the problem]

To solve the above-mentioned problem, the invention of technical solution 1 is a substrate processing method for drying a substrate formed with a pattern, which is characterized by comprising: a supply step, in which a processing liquid is supplied to the surface of the above-mentioned substrate; and a light irradiation step, in which the surface of the above-mentioned substrate is heated by irradiating light to the surface of the above-mentioned substrate to evaporate the above-mentioned processing liquid; and in the above-mentioned light irradiation step, the drying time required from the time when the capillary force starts to act on the above-mentioned pattern to the time when the above-mentioned processing liquid is removed from the surface of the above-mentioned substrate is a short time that is shorter than the collapse time required from the time when the capillary force starts to act on the above-mentioned pattern to the time when the above-mentioned pattern collapses.

Furthermore, the invention of technical solution 2 is a substrate processing method as disclosed in technical solution 1, wherein in the light irradiation step, a flash light is irradiated from a flash lamp onto the surface of the substrate.

Furthermore, the invention of technical solution 3 is a substrate processing method as in the invention of technical solution 2, wherein in the light irradiation step, the energy of the irradiated flash is adjusted according to the pillar spacing between adjacent pillars in the pattern.

Furthermore, the invention of technical solution 4 is a substrate processing method as disclosed in technical solution 3, wherein in the light irradiation step, the narrower the spacing between the pillars, the greater the energy of the irradiated flash.

Furthermore, the invention of technical solution 5 is a substrate processing method as in any one of the inventions of technical solutions 2 to 4, wherein in the light irradiation step, the irradiation light with a wavelength below 400 nm is a cut-off flash.

Furthermore, the invention of technical solution 6 is a substrate processing method as in any one of the inventions of technical solutions 1 to 5, wherein in the light irradiation step, the surface of the substrate is irradiated with laser light.

Furthermore, the invention of technical solution 7 is a substrate processing method as in any one of the inventions of technical solutions 1 to 6, wherein the processing liquid is isopropyl alcohol.

In addition, the invention of technical solution 8 is a substrate processing device for drying a substrate formed with a pattern, which is characterized in that it comprises: a substrate holding part, which holds the above-mentioned substrate; a processing liquid supplying part, which supplies processing liquid to the surface of the above-mentioned substrate; and a light irradiation part, which heats the surface of the above-mentioned substrate by irradiating light to the surface of the above-mentioned substrate to evaporate the above-mentioned processing liquid; the drying time required from the time when the capillary force starts to act on the above-mentioned pattern to the time when the above-mentioned processing liquid is removed from the surface of the above-mentioned substrate is a short time that is shorter than the collapse time required from the time when the capillary force starts to act on the above-mentioned pattern to the time when the above-mentioned pattern collapses.

Furthermore, the invention of technical solution 9 is a substrate processing device as in the invention of technical solution 8, wherein the light irradiation section has a flash lamp for irradiating flash light to the surface of the substrate.

Furthermore, the invention of technical solution 10 is a substrate processing device as in the invention of technical solution 9, wherein the energy of the flash irradiated from the above-mentioned flash lamp is adjusted according to the pillar spacing between adjacent pillars in the above-mentioned pattern.

Furthermore, the invention of technical solution 11 is a substrate processing device like the invention of technical solution 10, wherein the narrower the spacing between the pillars, the greater the energy of the flash irradiated from the flash lamp.

Furthermore, the invention of technical solution 12 is a substrate processing device as in any one of the inventions of technical solutions 9 to 11, further comprising a filter disposed between the illumination portion and the substrate holding portion to cut off light with a wavelength below 400 nm from the flash light emitted from the flash lamp.

Furthermore, the invention of technical solution 13 is a substrate processing device as in any one of the inventions of technical solutions 8 to 12, wherein the light irradiation unit irradiates the surface of the substrate with laser light.

Furthermore, the invention of technical solution 14 is a substrate processing device as in any one of the inventions 8 to 13, wherein the processing liquid is isopropyl alcohol. [Effect of the invention]

According to the invention of technical solutions 1 to 7, the drying time required from the start of capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate is shorter than the collapse time required from the start of capillary force acting on the pattern to the collapse of the pattern. Therefore, even for patterns that are relatively large in length and width, the collapse of the pattern can be reliably suppressed.

In particular, according to the invention of technical solution 4, since the energy of the flash irradiated is greater when the interval between the pillars is narrower, the drying time can be surely made shorter than the collapse time, and the collapse of the pattern can be more surely suppressed.

In particular, according to the invention of technical solution 5, since the irradiation light with a wavelength below 400 nm is cut off by the flash, damage to the substrate can be suppressed.

According to the invention of technical solutions 8 to 14, the drying time required from the start of capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate is shorter than the collapse time required from the start of capillary force acting on the pattern to the collapse of the pattern. Therefore, even for patterns that are relatively large in length and width, the collapse of the pattern can be reliably suppressed.

In particular, according to the invention of technical solution 11, since the narrower the pillar interval is, the greater the energy of the flash irradiated from the flash lamp is, the drying time can be surely made shorter than the collapse time, and the collapse of the pattern can be more surely suppressed.

In particular, according to the invention of technical solution 12, since a filter is further provided between the light irradiation part and the substrate holding part and cuts off light with a wavelength below 400 nm from the flash light emitted by the flash lamp, damage to the substrate can be suppressed.

Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) not only strictly indicate the positional relationship, but also indicate a state of relative displacement of angles or distances within a tolerance or a range that can achieve the same degree of function, unless otherwise specified. Furthermore, expressions indicating an equal state (e.g., "same," "equal," "homogeneous," etc.) not only strictly indicate an equal state quantitatively, but also indicate a state of difference in tolerance or a range that can achieve the same degree of function, unless otherwise specified. Furthermore, expressions indicating shapes (e.g., "circular", "quadrilateral", "cylindrical", etc.), unless otherwise specified, not only indicate the shapes strictly in terms of geometry, but also indicate shapes within a range that can achieve the same degree of effect, such as concave-convex or chamfered corners. Furthermore, expressions such as "equipped", "equipped", "equipped", "including", and "having" constituent elements are not exclusive expressions that exclude the presence of other constituent elements. Furthermore, the expression "at least one of A, B, and C" includes "only A", "only B", "only C", "any two of A, B, and C", and "all of A, B, and C".

FIG. 1 is a schematic top view for explaining the internal layout of a single-wafer cleaning device 100 equipped with a substrate processing device of the present invention. The single-wafer cleaning device 100 is a device for sequentially cleaning substrates W one by one. The substrate W to be processed is a semiconductor substrate in the shape of a silicon disk. In addition, in FIG. 1 and subsequent figures, the size or quantity of each part is exaggerated or simplified as needed for easy understanding.

The single-wafer cleaning device 100 performs a surface cleaning process on the substrate W by spraying a chemical solution and a cleaning solution on the surface of the substrate W, and then performs a drying process on the substrate W. The chemical solution mentioned above includes, for example, a liquid for etching or a liquid for removing particles, and specifically, SC-1 liquid (a mixed solution of ammonium hydroxide, hydrogen peroxide and pure water), SC-2 liquid (a mixed solution of hydrochloric acid, hydrogen peroxide and pure water), buffered hydrofluoric acid (BHF) or dilute hydrofluoric acid (DHF) is used. In addition, as a cleaning solution, pure water is typically used. In the following description, chemical solutions, cleaning solutions and organic solvents are collectively referred to as "processing solutions".

The single-wafer cleaning apparatus 100 includes a plurality of processing units 1 and 101 , a loading port LP, a carrier robot 102 , a main transport robot 103 , and a control unit 90 .

The carrier C containing a plurality of substrates W processed by the single-wafer cleaning device 100 is placed on the loading port LP. The carrier C containing unprocessed substrates W is transported and placed on the loading port LP by an unmanned transport vehicle (AGV (Automated Guided Vehicle), OHT (Overhead Hoist Transfer)) or the like. In addition, the carrier C containing processed substrates W is also taken away from the loading port LP by the unmanned transport vehicle.

Typically, carrier C is a FOUP (Front Opening Unified Pod) that stores substrates W in a closed space. Carrier C uses multiple retaining frames formed inside it to hold multiple substrates W arranged in a horizontal position (normal to the main surface of substrate W along the vertical direction) in a certain interval in the vertical direction. The maximum number of wafers that carrier C can accommodate is 25 or 50. In addition, as a form of carrier C, in addition to FOUP, it can also be a SMIF (Standard Mechanical Interface) box or an OC (open cassette) that exposes the stored substrates W to the atmosphere.

The carrier robot 102 is configured to slide, rotate, and move the hand holding the substrate W forward and backward. The carrier robot 102 transports the substrate W between the carrier C and the main transport robot 103. The carrier robot 102 takes out the unprocessed substrate W from the carrier C and delivers it to the main transport robot 103. In addition, the carrier robot 102 receives the processed substrate W from the main transport robot 103 and stores it in the carrier C.

The main transport robot 103 is configured to be capable of rotating, lifting, and advancing and retreating the arm holding the substrate W. The main transport robot 103 carries the substrate W received from the carrier robot 102 into either the processing unit 1 or the processing unit 101. In addition, the main transport robot 103 delivers the substrate W carried out from either the processing unit 1 or the processing unit 101 to the carrier robot 102. In addition, the main transport robot 103 sometimes also carries the substrate W between the processing unit 1 and the processing unit 101. For example, the main transport robot 103 carries the substrate W carried out from the processing unit 101 into the processing unit 1.

The processing unit 101 performs a cleaning process on one substrate W. The processing unit 1 performs a drying process on one substrate W. In the single-wafer cleaning device 100 of this embodiment, a total of 12 processing units 101 or processing units 1 are mounted. Specifically, four towers are arranged in a manner of surrounding the main transport robot 103, each of which is formed by stacking three processing units (processing units 101 or processing units 1) in the vertical direction. In FIG. 1, one layer of the processing units stacked in three layers is schematically shown, and one processing unit 1 and three processing units 101 are arranged in a manner of surrounding the main transport robot 103. In addition, the number of processing units in the single-wafer cleaning device 100 is not limited to 12, and may be appropriately changed.

Next, the processing unit 1 mounted on the single-wafer cleaning device 100 is described. The substrate processing device of the present invention is a processing unit 1 that performs a drying process on the substrate W after the cleaning process. FIG. 2 is a side view showing the main components of the processing unit 1. The processing unit 1 mainly includes a processing chamber 10, a rotation holding part 20, a processing liquid nozzle 30, a light irradiation part 50 and a control part 90.

The processing chamber 10 is a hollow frame. A rotation holding unit 20 and a processing liquid nozzle 30 are provided inside the processing chamber 10. When processing a substrate, the processing chamber 10 accommodates a substrate W to be processed.

A loading/unloading port (not shown) is provided in the processing chamber 10. The loading/unloading port is opened and closed by a shutter. When the loading/unloading port is open, the main transfer robot 103 loads and unloads the substrate W in and out of the processing chamber 10. During the processing of the substrate W, the loading/unloading port is closed.

The rotation holding part 20 has a rotation chuck 22 and a rotation motor 25. The rotation chuck 22 is a substrate holding part that holds the substrate W in a horizontal position. The rotation chuck 22 in this embodiment is a vacuum adsorption type chuck. The rotation chuck 22 adsorbs and holds the central part of the lower surface of the substrate W. In addition, the rotation chuck 22 can also be a clamping type mechanical chuck or other types of chucks.

The spin chuck 22 has a disk shape having a diameter smaller than that of the substrate W. When the lower surface of the substrate W is held by the spin chuck 22 by suction, the peripheral portion of the substrate W protrudes outward from the outer peripheral end of the spin chuck 22 .

The rotary chuck 22 is connected to the rotary motor 25 via the rotary shaft 27. That is, the upper end of the rotary shaft 27 of the rotary motor 25 is connected to the center of the lower surface of the rotary chuck 22. When the rotary motor 25 rotates the rotary shaft 27 while the substrate W is adsorbed and held on the rotary chuck 22, the substrate W and the rotary chuck 22 rotate around the rotary shaft A1 in the vertical direction in the horizontal plane.

The cup 40 is disposed so as to surround the spin chuck 22. The cup 40 has a cylindrical shape, and the upper portion of the cup 40 is inclined so as to get closer to the spin chuck 22 as it goes upward. However, the inner diameter of the upper end portion of the cup 40 is larger than the diameter of the substrate W. The upper end of the cup 40 is higher than the height position of the substrate W held by the spin chuck 22. Therefore, the liquid scattered from the substrate W rotated by the spin motor 25 due to the centrifugal force is received by the cup 40 and recovered. The liquid recovered by the cup 40 is discharged from the drain pipe 45 disposed at the bottom of the cup 40. In addition, the cup 40 may also be a multi-layer structure having a plurality of recovery ports classified according to purpose.

The processing liquid nozzle 30 is mounted on the front end of a rod-shaped nozzle arm 31 extending in the horizontal direction. The nozzle arm 31 is supported by an arm support shaft 32 extending in the vertical direction. The arm support shaft 32 is connected to the nozzle drive unit 33. The nozzle drive unit 33 rotates the arm support shaft 32 around the rotation axis A2 along the vertical direction. When the nozzle drive unit 33 rotates the arm support shaft 32, the nozzle arm 31 rotates, and the processing liquid nozzle 30 moves along an arc trajectory between a standby position on the outside of the cup 40 and a processing position above the substrate W held on the rotary chuck 22.

In addition, the nozzle driving part 33 moves the arm support shaft 32 and the nozzle arm 31 upward and downward. Thereby, the processing liquid nozzle 30 also moves up and down along the lead vertical direction.

The processing liquid is transported from a processing liquid supply source (not shown) to the processing liquid nozzle 30. The processing liquid nozzle 30 ejects the transported processing liquid downward. The processing liquid nozzle 30 ejects the processing liquid to the processing position above the substrate W, thereby supplying the processing liquid to the surface of the substrate W. In this embodiment, the processing liquid nozzle 30 supplies IPA (isopropyl alcohol) to the substrate W as the processing liquid.

The light irradiation unit 50 is disposed above the processing chamber 10. The light irradiation unit 50 includes a light source including a plurality of xenon flash lamps FL and a reflector 52 disposed to cover the light source. Alternatively, the light irradiation unit 50 may be disposed above the processing chamber 10 in a lamp room independent of the processing chamber 10.

The plurality of flash lamps FL are rod-shaped lamps each having a long cylindrical shape, and are arranged in a plane in such a manner that the length direction of each flash lamp FL is parallel to each other along the main surface (i.e., in the horizontal direction) of the substrate W held by the rotation holding portion 20. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

The xenon flash lamp FL has: a cylindrical glass tube (discharge tube) with xenon gas sealed inside and an anode and a cathode connected to a capacitor at both ends; and a trigger electrode attached to the outer circumference of the glass tube. Since xenon gas is an electrical insulator, even if there is charge stored in the capacitor, the electricity does not flow in the glass tube under normal conditions. However, when a high voltage is applied to the trigger electrode to destroy the insulation, the electricity stored in the capacitor flows instantly in the glass tube, and light is emitted by the excitation of xenon atoms or molecules at this time. Such a xenon flash lamp FL has the following characteristics: since the electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse of 0.1 milliseconds to 100 milliseconds, it can emit extremely strong light compared to halogen lamps, etc. That is, the flash lamp FL emits flash light within an irradiation time of 0.1 milliseconds to 100 milliseconds.

Furthermore, the reflector 52 is disposed above the plurality of flash lamps FL in a manner covering the entirety of the plurality of flash lamps FL. The basic function of the reflector 52 is to reflect the flash light emitted from the plurality of flash lamps FL to the lower side. The reflector 52 is formed of an aluminum alloy plate, and its surface (the surface facing the flash lamp FL side) is roughened by sandblasting.

Each of the plurality of flash lamps FL is supplied with electric power from a power supply unit 60. The power supply unit 60 includes a capacitor or a coil. The power supply unit 60 applies a preset voltage to the capacitor to store electric charge, and supplies the electric charge stored in the capacitor to the flash lamp FL when the flash is irradiated.

The energy of the flash emitted from the flash light FL is determined by the energy stored in the capacitor of the power supply unit 60. When the capacitor of the electrostatic capacitance C is charged with the charging voltage V, the energy stored in the capacitor becomes CV ² /2. Since the electrostatic capacitance C is a constant inherent to the capacitor, the energy stored in the capacitor can be adjusted by the charging voltage V. In addition, an IGBT (Insulated Gate Bipolar Transistor) can be provided in the power supply unit 60, and the waveform of the current flowing in the flash light FL can be determined by the IGBT to adjust the lighting time of the flash light FL.

An optical filter 70 is provided between the light irradiation unit 50 and the rotation holding unit 20. The optical filter 70 cuts off ultraviolet light having a wavelength of 400 mm or less from the flash light emitted from the flash lamp FL.

The control unit 90 controls various action mechanisms provided in the single-chip cleaning device 100. The control unit 90 also controls the action of the processing unit 1. The hardware structure of the control unit 90 is the same as that of a general computer. That is, the control unit 90 has a circuit for performing various calculations, namely a CPU (Central Processing Unit), a memory dedicated to reading out basic programs, namely a ROM (Read Only Memory), a memory that can read and write freely for storing various information, namely a RAM (Random Access Memory), and a storage unit 91 (such as a disk or SSD (Solid State Drive)) that pre-stores control software or data. The control unit 90 is electrically connected to the rotary motor 25 of the rotation holding unit 20 or the nozzle driving unit 33 to control the actions thereof.

A conversion table 93 is stored in the memory unit 91 of the control unit 90. In the conversion table 93, the correlation between the pillar spacing formed in the pattern of the substrate W and the charging voltage applied to the flash lamp FL is registered. The control unit 90 controls the power supply unit 60 in such a manner that the capacitor is charged by the charging voltage V obtained from the conversion table 93. In addition, the control using the conversion table 93 will be described later.

Next, the processing operation of the processing unit 1 mounted in the single-wafer cleaning device 100 will be described. Fig. 3 is a flow chart showing the processing sequence in the processing unit 1. In this embodiment, a nanostructure pattern is formed on a substrate W that is a processing object.

FIG. 4 is a diagram showing a pattern formed on a substrate W. The base portion 81 of the substrate W is a flat silicon disk-shaped member. On the surface of the base portion 81 of the substrate W, a plurality of slender cylindrical pillars 85 are erected to form a nanostructure pattern. In this embodiment, for example, the diameter d of the cylindrical pillar 85 is 30 nm and the height h is 600 nm. That is, the aspect ratio of the nanostructure pattern is 20. Furthermore, for example, the pillar spacing p between adjacent pillars 85 is 60 nm. The substrate W formed with the nanostructure pattern formed by the plurality of pillars 85 is carried into the single-chip cleaning device 100 for processing.

Returning to FIG. 3 , before the processing in the processing unit 1, the processing unit 101 performs a cleaning process on the substrate W (step S1). First, the carrier robot 102 takes out an unprocessed substrate W from the carrier C of the loading port LP and hands it over to the main transport robot 103, and the main transport robot 103 moves the received substrate W into the processing unit 101. The surface of the substrate W is cleaned in the processing unit 101. Specifically, after a chemical solution is supplied to the rotating substrate W for cleaning to remove particles, pure water is supplied to the surface of the substrate W for cleaning. After the cleaning process using the processing solution is completed, the substrate W is moved out of the processing unit 101 by the main transport robot 103 and moved into the processing unit 1. Since the substrate W just after the cleaning process has the processing liquid attached to it, the substrate W is dried in the processing unit 1. Alternatively, the substrate W after the cleaning process may be spun and dried at high speed in the processing unit 101, but in this case, the water cannot be completely removed from the substrate W, so the drying process of the processing unit 1 is required.

The main transfer robot 103 carries the cleaned substrate W into the processing chamber 10 and holds it on the rotary chuck 22 (step S2). The rotary chuck 22 sucks the center of the lower surface of the carried substrate W and holds the substrate W in a horizontal position.

After holding the substrate W on the rotary chuck 22, the processing liquid nozzle 30 moves from the standby position on the outside of the cup 40 to the processing position above the substrate W. In addition, the rotation of the substrate W is started by the rotary motor 25. Next, the processing liquid nozzle 30 supplies the processing liquid to the surface of the substrate W (step S3). In the present embodiment, the processing liquid nozzle 30 supplies IPA (isopropyl alcohol) as the processing liquid. The processing liquid nozzle 30 supplies 20 ul of IPA to every 1 ^cm2 of the surface of the substrate W. The surface tension of IPA is smaller than the surface tension of water. By supplying IPA, the water attached to the substrate W is replaced by IPA. After supplying a specified amount of IPA, the processing liquid nozzle 30 returns from the processing position to the standby position again.

FIG. 5 is a diagram showing the state of the substrate W just after IPA is supplied. At the time point just after IPA is supplied, the liquid level of IPA is higher than the upper end of the pillar 85. That is, the plurality of pillars 85 are all immersed in the liquid of IPA. In this way, when the plurality of pillars 85 are all in the liquid of IPA, no capillary force is generated because no curved liquid surface is formed between adjacent pillars 85. Therefore, there is no stress acting on the plurality of pillars 85, and the pillars 85 will not be deformed and collapse. In addition, during the cleaning process in the processing unit 101, since the pillars 85 are all in the processing liquid, there is no risk of pattern collapse.

As the substrate W supplied with IPA rotates, the IPA spreads thinly and is applied to the entire surface of the substrate W. Furthermore, due to the centrifugal force accompanying the rotation of the substrate W, a portion of the IPA above the upper end of the support 85 is scattered from the substrate W. In this way, preliminary drying of the substrate W is performed (step S4). The preliminary drying is to remove a portion of the IPA above the upper end of the support 85. In this embodiment, preliminary drying is performed by the scattering of the IPA accompanying the rotation of the substrate W and the evaporation of the IPA. The period for preliminary drying is at least the period when the liquid level of the IPA becomes above the upper end of the support 85. In addition, as preliminary heating, for example, the evaporation of the IPA can be promoted by blowing warm air to the substrate W. Alternatively, it may be pre-drying in which the IPA evaporates only by natural drying.

By pre-drying, the liquid level of IPA gradually decreases, and finally the liquid level of IPA is consistent with the upper end of the support 85. FIG6 is a diagram showing the state of the substrate W when the liquid level of IPA is consistent with the upper end of the support 85. When the liquid level of IPA decreases to a height position consistent with the upper end of the support 85, a curved liquid surface is formed between adjacent supports 85. When the curved liquid surface is formed, capillary force acts on the supports 85 on both sides of the curved liquid surface.

In this embodiment, at the time when the liquid level of IPA is consistent with the upper end of the support 85, the flash lamp FL irradiates the surface of the substrate W with a flash (step S5). By irradiating the substrate W with a very short and strong flash with an irradiation time of 0.1 milliseconds to less than 100 milliseconds (5 milliseconds in this embodiment), the surface of the substrate W is instantly heated strongly, and a large amount of heat energy is applied to the IPA remaining on the surface. By instantly applying heat energy greater than the evaporation heat required to evaporate the IPA remaining on the surface of the substrate W, the IPA evaporates instantly and the substrate W is dried. That is, by evaporating the IPA faster than the pattern collapses due to capillary force, the substrate W can be dried without collapsing the pattern. Furthermore, when the flash light is irradiated, the processing liquid nozzle 30 is located at a standby position on the outer side of the cup 40, and the rotation of the substrate W is stopped.

After the drying process of the substrate W is completed, the main transfer robot 103 carries the substrate W out of the processing chamber 10 (step S6). Thereafter, the substrate W is handed over from the main transfer robot 103 to the carrier robot 102 and returned to the carrier C.

In this embodiment, the liquid surface of IPA is consistent with the upper end of the support 85, and the flash is irradiated at the time when the capillary force of the curved liquid surface begins to act on the pattern, so that the residual IPA evaporates instantly. In the case of no flash, after the liquid surface of IPA is consistent with the upper end of the support 85, the movement of the liquid surface due to the interaction of the capillary force is dominant. In this way, as shown in FIG. 7, the liquid surface level is different between the supports 85. It is more ideal that the liquid surface level is more uniform even after the liquid surface of IPA is consistent with the upper end of the support 85, but if not, the liquid surface level will definitely be different.

If the liquid level is uniform, the capillary force acting on each support 85 from the periphery is also uniform, and the support 85 does not deform. However, if a difference in the liquid level occurs as shown in FIG. 7 , the balance of the capillary force acting on each support 85 is destroyed, and the support 85 deforms. Furthermore, if the deformation degree of the support 85 increases, as shown in FIG. 8 , the support 85 contacts the adjacent support 85, and the pattern collapses.

Therefore, in this embodiment, the flash irradiation is performed as follows, that is, the IPA is evaporated at a speed faster than the speed at which the liquid surface level is differentiated by the interaction of the capillary force. In other words, by irradiating the flash with a very short irradiation time and a relatively strong intensity, the drying time required from the start of the capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate W is made shorter than the collapse time required from the start of the capillary force acting on the pattern to the collapse of the pattern. In addition, the pattern collapses when the support 85 is deformed and contacts the adjacent support 85.

In this way, the substrate W is dried at a faster speed than the speed at which the difference in the liquid surface level is generated due to the interaction of capillary forces, thereby reliably suppressing pattern collapse even in the next generation nanostructure with a relatively large length and width.

FIG9 is a graph showing the correlation between the drying speed and the pattern collapse rate. In the figure, the cross mark indicates the natural drying of IPA only, the drying speed is the slowest, and the pattern collapse rate is also high. The square mark indicates the case where nitrogen at room temperature is blown to IPA. Although the drying speed is slightly faster than natural drying, the collapse rate is also high. On the other hand, the triangle mark indicates the case where IPA is heated normally. The drying speed is quite fast, but the collapse rate is still high. In contrast, the circle mark indicates the case where IPA is flash-irradiated as in the present embodiment. The drying speed is extremely high and the pattern collapse rate becomes low.

Furthermore, in the present embodiment, the energy of the flash is adjusted according to the pillar spacing p between the adjacent pillars 85 in the pattern. As described above, in the present embodiment, the flash is irradiated in such a manner that the drying time required from the start of the capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate W is shorter than the collapse time required from the start of the capillary force acting on the pattern to the collapse of the pattern. The collapse time required until the collapse of the pattern is the time required from the start of the deformation of the pillar 85 to the contact with the adjacent pillar 85, and the smaller the pillar spacing p, the shorter the time. Therefore, the narrower the pillar spacing p, the shorter the drying time needs to be, and the larger the energy of the irradiated flash must be. Specifically, the narrower the pillar spacing p, the greater the charging voltage V applied to the capacitor of the power supply unit 60.

FIG. 10 is a diagram showing a conversion table 93 in which the correlation between the pillar spacing p and the required charging voltage V is recorded. The correlation between the pillar spacing p and the required charging voltage V is obtained in advance by experiments or simulations, and the conversion table 93 is prepared based on this. The prepared conversion table 93 is stored in the memory unit 91 of the control unit 90 (see FIG. 2 ). As shown in FIG. 10 , the conversion table 93 records the correlation that the narrower the pillar spacing p, the larger the required charging voltage V.

The control unit 90 reads the charging voltage V corresponding to the pillar spacing p in the pattern formed on the substrate W from the conversion table 93, and controls the power source 60 in such a manner that the capacitor is charged by the charging voltage V. In this way, by irradiating the flash with appropriate energy corresponding to the pillar spacing p in the pattern formed on the substrate W, the drying time can be made shorter than the above-mentioned collapse time, and the pattern collapse can be surely suppressed. In addition, the pillar spacing p in the pattern can be described in the processing recipe, for example.

In addition, in this embodiment, an optical filter 70 is provided to cut off light with a wavelength of 400 nm or less from the flash. When the light emitted from the flash lamp FL passes through the optical filter 70, the light with a wavelength of 400 nm or less is removed from the flash. Therefore, the flash after removing the ultraviolet light with a wavelength of 400 nm or less is irradiated on the surface of the substrate W. The chemical action of ultraviolet light with a wavelength of 400 nm or less is more significant. By cutting off such light with a wavelength of 400 nm or less from the flash, it is possible to suppress the damage of the pattern caused by the extremely strong flash.

Although the embodiments of the present invention have been described above, the present invention can be modified in various ways other than the above as long as it does not deviate from the main purpose. For example, in the above embodiments, although IPA is supplied to the substrate W as the processing liquid, it is not limited to this, and other types of processing liquids can also be supplied. For example, pure water can be supplied to the substrate W from the processing liquid nozzle 30 as the processing liquid, and then flash light is irradiated to evaporate the pure water. However, since the evaporation heat of IPA is lower than that of pure water, and the surface tension is also smaller, the use of IPA as in the above embodiments can dry the substrate W with a flash of smaller energy, and the pattern is not easy to collapse.

Furthermore, in the above-mentioned embodiment, the flash light from the flash lamp FL is irradiated to the substrate W coated with IPA to achieve a drying time shorter than the collapse time, but instead of this, laser light may be irradiated to the surface of the substrate W. The irradiation time of laser light is also very short and the intensity is relatively strong. Therefore, even if the substrate W coated with IPA is irradiated with laser light, the drying time can be made shorter than the collapse time, and the pattern collapse can be suppressed.

Furthermore, in the above-mentioned embodiment, the flash is irradiated at the time when the liquid level of IPA is consistent with the upper end of the support 85, but the flash can also be irradiated on the surface of the substrate W before the liquid level of IPA is consistent with the upper end of the support 85. That is, the flash can also be irradiated on the substrate W when the liquid level of IPA is higher than the upper end of the support 85. Based on this viewpoint, the preliminary drying of the above-mentioned embodiment is not a necessary step, and the flash can be irradiated without preliminary drying. However, in this case, because the amount of IPA remaining on the surface of the substrate W increases, the evaporation heat required for its complete evaporation is greater than that of the above-mentioned embodiment, so in order to apply heat energy greater than the evaporation heat, the energy of the flash must be further increased. Therefore, as in the above-mentioned embodiment, it is best to irradiate the flash at the time when the liquid level of IPA is consistent with the upper end of the support 85.

Furthermore, in the above-mentioned embodiment, the cleaning process of the substrate W is performed in the processing unit 101, and the drying process is performed in the processing unit 1, but both the cleaning process and the drying process may be performed in one processing unit. Specifically, for example, a cleaning liquid nozzle for spraying a cleaning liquid may be further provided in the processing unit 1, and the cleaning process and the drying process of the substrate W may be performed continuously in the processing unit 1.

1: Processing unit 10: Processing chamber 20: Rotation holding unit 22: Rotation chuck 25: Rotation motor 27: Rotation shaft 30: Processing liquid nozzle 31: Nozzle arm 32: Arm support shaft 33: Nozzle drive unit 40: Cup 45: Drain pipe 50: Light irradiation unit 52: Reflector 60: Power supply unit 70: Optical filter 81: Base unit 85: Support 90: Control unit 91: Memory unit 93: Conversion table 100: Single-wafer cleaning device 101: Processing unit 102: Carrier robot 103: Main transport robot A1: Rotation axis A2: Rotation axis C: Carrier d: Diameter FL: Flash light h: Height LP: Loading port p: Spacing S1~S6: Steps W: Substrate

FIG. 1 is a schematic top view for explaining the internal layout of a single-wafer cleaning device equipped with the substrate processing device of the present invention. FIG. 2 is a side view showing the main structure of the substrate processing device of the present invention. FIG. 3 is a flow chart showing the processing sequence of the processing unit. FIG. 4 is a diagram showing a pattern formed on a substrate. FIG. 5 is a diagram showing the state of a substrate just after IPA is supplied. FIG. 6 is a diagram showing the state of a substrate when the liquid level of IPA is consistent with the upper end of a support. FIG. 7 is a diagram showing a state where the liquid level of IPA is different. FIG. 8 is a diagram showing a state where a pattern collapses. FIG. 9 is a diagram showing the correlation between the drying speed and the pattern collapse rate. FIG. 10 is a diagram showing a conversion table recording the relationship between the pillar spacing and the required charging voltage.

1: Processing unit

10: Processing chamber

20: Rotation holding unit

22: Rotating chuck

25: Rotary motor

27: Rotation axis

30: Treatment fluid nozzle

31: Nozzle arm

32: Arm support shaft

33: Nozzle drive unit

40: cup

45: Drain pipe

50: Light irradiation part

52:Reflector

60: Power unit

70:Optical filter

90: Control Department

91: Memory Department

93:Conversion table

A1: Rotation axis

A2: Rotation axis

FL: Flash light

W: Substrate

Claims (8)

A substrate processing method is characterized in that: it dries a substrate formed with a pattern, and comprises: a supply step of supplying a processing liquid to the surface of the substrate; and a light irradiation step of irradiating the surface of the substrate with light to heat the surface and evaporate the processing liquid; and in the light irradiation step, the drying time required from the start of capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate is shorter than the collapse time required from the start of capillary force acting on the pattern to the collapse of the pattern; and in the light irradiation step, a flash is irradiated from a flash lamp to the surface of the substrate; and in the light irradiation step, the energy of the irradiated flash is adjusted according to the pillar spacing between adjacent pillars in the pattern. As in the substrate processing method of claim 1, in the light irradiation step, the narrower the spacing between the pillars, the greater the energy of the irradiated flash. A substrate processing method as claimed in claim 1, wherein in the above light irradiation step, the irradiation light with a wavelength below 400nm is cut off by flash. As in claim 1, the substrate processing method, wherein the processing liquid is isopropyl alcohol. A substrate processing device is characterized in that: it dries a substrate formed with a pattern, and comprises: a substrate holding part for holding the substrate; a processing liquid supply part for supplying processing liquid to the surface of the substrate; and a light irradiation part for irradiating light to the surface of the substrate to heat the surface and evaporate the processing liquid; and the drying time required from the start of capillary force acting on the pattern to the removal of the processing liquid from the surface of the substrate is shorter than the collapse time required from the start of capillary force acting on the pattern to the collapse of the pattern; and the light irradiation part has a flash lamp for irradiating flash light to the surface of the substrate; and the energy of the flash light irradiated from the flash lamp is adjusted according to the pillar spacing between adjacent pillars in the pattern. As in claim 5, the substrate processing device, wherein the narrower the spacing between the pillars, the greater the energy of the flash emitted from the flash lamp. The substrate processing device of claim 5 further comprises: a filter disposed between the illumination unit and the substrate holding unit, and the flash light emitted from the flash lamp cuts off light with a wavelength below 400nm. A substrate processing device as claimed in any one of claims 5 to 7, wherein the processing liquid is isopropyl alcohol.